The subject matter described herein relates generally to gas turbine engines and, more particularly, to a bucket assembly for use with a turbine engine.
At least some known gas turbine engines include a combustor, a compressor coupled downstream from the combustor, a turbine, and a rotor assembly rotatably coupled between the compressor and the turbine. At least some known rotor assemblies include a plurality of nozzle vanes, a rotor shaft, at least one rotor disk coupled to the rotor shaft, and a plurality of circumferentially-spaced turbine buckets that are coupled to each rotor disk. Each turbine bucket includes an airfoil that extends radially outward from a platform towards a turbine casing.
During operation of at least some known turbines, the compressor compresses air, that is mixed with fuel and channeled to the combustor. The mixture is then ignited generating hot combustion gases that are then channeled to the turbine. The nozzle vanes direct high-temperature fluids, such as combustion gases towards the turbine blades. The rotating turbine blades or buckets channel combustion gases through the turbine. The turbine extracts energy from the combustion gases for powering the compressor, producing useful work to power a load, such as an electrical generator, or to propel an aircraft in flight.
Furthermore, the airfoil portions of at least some known rotor blades are generally exposed to higher temperatures than the dovetail portions. Higher temperatures may cause steep thermal gradients to develop at the interface between the airfoil and the platform, and/or between the shank and the platform. These temperature gradients may cause compressive thermal stresses to be induced to the rotor blade platform. Over time, continued operation in high temperature and high stress conditions may cause platform oxidation, platform cracking, and/or platform creep deflection, any or all of which may shorten the useful life of the rotor assembly.